Riveted structure and machine for producing the same



Oct. 14, 1930. J. EIRALGREN 1,778'498 RIVETED STRUCTURE AND MACHINE FOR PRODUCING THE SAME Filed March-12, 1927 3Sheets-Sheet 1 Oct. 14, 1930. J. E. KALGREN 1,778,498

RIVETED STRUCTURE AND MACHINE FOIIPRODUCING' THE SAME Filed March 12, 1927 3 Sheets-Sheet 2 lbmzz m/ .7051: E170] e1] Oct. 14,1930. J. E. KALGREN 1,

' RIVETED STRUCTURE AND MACHINE FOR PRODUCING THE- SAME Filed March 12, 1927 3. Sheets-Sheet 3 1.7m Jolm J10] 15 Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE I JOHN E. KALGREN, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO J. R. CLARK COMPANY, OF MINNEAPOLIS, MINNESOTA, A CORPORATION OF MINNESOTA RIVETED STRUCTURE AND MACHINE FOR rnonncrne THE SAME,

Application filed March 12, 1927. Serial No. 174,995.

My present invention relates primarily to a riveted structure and the process of producing the same and has for its object to form a mushroom head on a rivetinserted through a compressible member, such as a piece of wood, to eliminate the use of a washer and increase the holding actionof the rivet and prevent the Wood from splitting. The mushroom head is'formed by setting up a whirling action on the end of a rivet, during which action the peripheral edge portion of the mushroom head is clinched into the wood by being turned down and then curved inwardly. During the formation of the mushroom head, the wood is compressed and thereafter held compressed by the rivet so that the rivet is held against endwise movement and will not loosen in'case of shrinkage of the wood.

' Said invention also has for its object to provide a simple and highly eflicient centering",

clamping and riveting machine for holding the parts of a structure to be connected by rivets and for. formingmushroom heads on the rivetsj The invention, while intended for general use, is especially well adapted for use in attaching the top step to step ladders and the machine illustrated is so designed.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a left side elevation of the machine having a step ladder positioned therein Fig. 2 is a transverse vertical section taken on the line 22 of Fig. 1 with the step ladder removed;

Fig. 3 is an enlarged fragmentary plan view of the machinein the vicinity of the line 33 of Fig. 1;

Fig. 4 is a view partly in front elevation and partly in section taken on the line -4 of Fig. 3

Fig. 5 is a'view partly in side elevation and partly in section taken on the line 55 of Fig. 3 with certain portions of the step ladder indicated by means of broken lines;

7 Fig. 6 is a detail view principally in section taken on the line 66 of Fig. 5, on an enlarged scale; and

Fig. 7 is a detail view principally in section taken on the line 7-7 of Fig. 3, on an enlarged scale.

The machine illustrated is for use in attaching the top step to a step ladder, 'and of the parts of the stepladder illustrated, it is important to note the side bars 8, steps 9, top step 10, knees 11 pressed from sheet metal, standards 12 pivoted to said knees and crossed bars 13 connecting said standards. The knees 11 are rigidly secured to the upper ends of the side bars 8 and have outturned apertured ears 14 on which the top step 10 rests and is secured by four rivets 15. These rivets 15 are passed upward through the apertured cars 14 and through bores in the top step 10 with their heads 15 .bearing against said ears and with the end portions of said rivets projecting above the top step 10. Certain of the parts of the step ladder, such as the spreader links and the pail shelf, are notshown as they have no bearing on this application. It may be here stated that the step ladder is substantially complete at the time the same is placed in the centering, clamping, and riveting machine, with the exception that the rivets connecting the top step 10 to the knees 11 have not been upset.

It is thought that the process will be best understood by a detail description of the machine and the use thereof.

The numeral 16 indicates a bed that is inclined from the rear to the front of the machine and is supported on legs 17 secured to a floor 18. Rigidly secured to the bed 16, at the longitudinal center thereof, is a housing '19 and back of this housing an electric motor 20 is mounted on the bed 16 and its armature shaft 21 extends into said housing from the back thereof.

At the front face of the housing 19 are four spinners in rectangular arrangement having spindles 22 which extend parallel to the armature shaft 21 and are journaled in the housing 19. These spindles 22 are simultaneously driven from the armature shaft 21 by suitable connections, not shown, in the housing 19. On the front end of each spindle 22, outward of the front face of the housing 19, is a bifurcated spinner head 23 in which is journaled a spinner wheel 24. In the periphery of the spinner wheel 24 is formed a circumferentially extended groove 25 that is concave in cross section. Said spinner wheel 24 comprises twoaxially spaced sections in rearward diverging relation from their rivetupsetting portions, as best shown in Figs. 6 and 7. The sections of the spinner wheel 24 are independently journaled on a screw stud 26 mounted in the prongs of the spinner head 23. A wedge-like spacer 27, formed with the spinner head 23, holds the sections of the spinner wheel 24 in diverging relation against inward axial movement and the prongs of the spinner head 23 hold the sections of the spinner wheel 24 against axial separation. It is important to note that the two sections of the spinner wheel. 24 are closely positioned at their rivet-engaging portions and arranged to engage arivet in axial alignment with its spindle 22.

A pair of horizontally spaced disc-like clamping heads 28 are located midway between the vertically spaced pairs of spinner heads 23. These clamping heads 28 are in a plane parallel to the front face of the housing 19 and are rigidly secured to the front ends of heavy stems 29 mounted for endwise movement in seats in said housing. Encircling each stem 29 is a coil spring 30 compressed between a shoulder on said stem and the front face of the housing 19. Stop collars 31 on the inner ends of the stems 29 normally engage the inner wall of the housing 19 and limit the projecting movements of the clamping heads 28 under the action of the springs 30.

On the left side of the housing 19 is a hand switch 32 with connections to the motor 20 for starting and stopping the same.

A carriage 33 is mounted on the bed 16, forward of the housing 19, for straight line sliding movement toward and from said housing. Formed with the rear end of the carriage 33 and extending thereabove is an upstanding U-shaped face plate 34 that is parallel to the front face of the housing 19 which in turn is prependicular to the bed 16. Formed with the carriage 33 and face plate 34 is a pair of upright webs 35, the inner faces of which are flush with the vertical inner edges of the uprights of said face plate.

(Jo-operating with each spinner wheel 24 is an abutment 36 having a concave rivet head seat 37 axia ly aligned with the spindle 22 of said head. hese abutments 36 also afford centering devices for positioning a step ladder placed horizontally between the up rights of the face plate 34 with the rivet heads 15 horizontally aligned with the rivet head seats 37. Said abutments are formed with the inner end portions of transversely extended slides 38 mounted in the upright members of the fare plate 34 and have dovetailed interlocking engagement therewith.

Set screws 39 in the uprights of the face plate 34 are arranged to impinge against the backs of the slides 38 and hold the same where set.

F or vertically positioning a step ladder held horizontally centered by the abutments 36 with the rivet heads 15 vertically aligned with the rivet head seats 37 there is provided a pair of adjustable abutments 40 inthe form ofuprightheadedscrews having threaded engagement with a pair of rearwardly projecting lugs 41 on the face plate 34. A pair of coil springs 42 are compressed between the housing 19 and face plate 34 and are under strain to hold the carriage 33 retracted with the abutments 36 spaced from the spinner wheels 24. Centering bosses 43 on the housing 19 and face plate 34 hold the springs 42 in position.

To manually move the carriage 33 toward the spinner wheels 24 against the tension of the springs 42 there is provided a foot treadle 44 pivoted to a standard 45 attached to the floor 18 and to the bed 16. A link 46 connects the foot trcadle 44 to the intermediate joint of a toggle lever 47 one link of which is pivoted to and between a pair of lugs 48 on the face plate 34, and the other link of which is pivoted to and etween a pair of upstanding lugs 49 formed with a block 50 slidably mounted on the bed 16 for straight line movement toward and from the face plate 34. Said block 50 has dovetailed interlocking engagement with the bed 16 and works in a large notch 51 formed in the carriage 33.

The block 50 is frictionally clamped to the bed 16 in different adjustments in respect to the face plate 34 by means of a nut-acting handle 52 arranged to impinge against the under side of the bed 16 and has a screw stud 53 that has threaded engagement with the block 50 and works in a longitudinally extended groove 54 in the bed 16. To further secure the block 50 to the bed 16 to resist pressure imparted thereto by a straightening movement of the toggle lever 47 during movement of the carriage 33 toward the spinner wheels 24, there is provided an abutment 55 in the form of a headed screw mounted in a block 56 slidably mounted on the bed 16 and having dovetailed interlocking engagement therewith. This block 56 is held where set by a set screw 57 having threaded engagement with said block and arranged to impinge against the bed 16. A coil spring 58, attached to the treadle 44 and anchored to the bed 16, is under strain to hold the treadle 44 raised and the toggle lever 47 buckled.

The purpose of making the block 56 detachable from the bed 16 is to permit the block 50 to be applied to said bed or detached therefrom. Mounted on the housing 19 is a counter 58 arranged to be actuated by connections 60 from the carriage 33.

To upset the rivets 15, the step ladder is placed in the machine in a horizontal posiion with the step ladder proper turned down and the step ladder support resting thereon. Nhen in the machine, the step ladder extends between the uprights of the face plate 34 and webs and with the-front edge of the top step 10 resting on the abutments 4O supporting the front end of the step ladder and with the side bars 8 resting in notches 61 formed in the carriage 33 and supporting the rear end portion of said ladder. In this position of the step ladder, the knees 11 extendbetween the abutments 36 which horizontally position said step ladder with the rivet heads 15 horizontally aligned with the rivet head seats 37. The abutments hold the top step 10 with the rivet heads 15 vertically aligned with the rivet head seats 37. With the rivet heads 15 thus centered in respect to the rivet head seats 37, the rivets 15 are axially aligned with the spinners. This alignment of the rivets 15 is absolutely necessary in order that no lateral movement will P be imparted to the rivets when upsetting the same which would cause said rivets to split the top step 10.

The purpose ofmounting the bed 16 in an inclined position is to hold the step ladder in substantially a horizontal position when in the machine, with the top step 10, which is transversely oblique to the side bars 8,paralleltothe face plate 34. It may be here stated that the webs 35 materially assist the operator in placing the step ladder into the machine in its proper relation thereto.

Vith the step ladder in the machine as described, the operator steps on the treadle 44 and presses the same down to straighten the toggle lever 47 by the link connection 46. This straightening action of the toggle lever 47 moves the carriage 33 toward the spinners. The initial movement of the carriage will carry the abutments 36 toward the top step 10 and thereby cause the rivet heads 15 to enter the rivet head seats 37. Further movement of the carriage 33 will cause the abutments 36, acting on the rivet heads 15 to press the same against the ears 14 and thereby cause the step ladder to move with the carriage. A still further movement of said carriage will bring the top step 10 into engagement with the clamping head 28 and retract the same against the tension of the springs 30. The pressure of the clamping heads 28 on the top step 10 will tightly press the same against the upper ends of the side bars 8, knees 11 and ears 14. Still further movement of the carriage 33 will bring the ends of the rivets 15 into contact with the spinner wheels 24 which will upset said rivets and form thereon mushroom heads 15*, as best shown in Fig. 7

Obviously, during the contact between the spinner wheels 24 and the rivets 15, to simultaneously upset said rivets, the two sections of each of said wheels will be rotated in opposite directions. During the formation of the mushroom heads 15 the same are tightly pressed against the upper face of the top step 10 with such force that said step will becompressed. At this same time the peripheral edge portions of the mushroom heads l5 will move away from the spinner wheels 24 and be turned into the wood and thence toward the rivets 15 to clinch said heads 15' at 15 in the top step 10.

What I claim is:

1. In a device of the class described, a spinner, a carriage for bodily moving a step ladder toward the spinner, a support radially spaced from the spinner for an upper step to be attached to said ladder for holding the same between the spinner and carriage substantially perpendicular to the axis of the spinner, and an abutment on the carriage arranged to engage the head of a rivet, loosely extending through apertures in a part of the step ladder and its upper step, to be fed to the spinner by the carriage.

2. The structure defined in claim 1 which further includes guides for positioning the step ladder on the carriage.

3. The structure defined in claim 1 which further includes a support on the carriage for the side bars of the step ladder intermediate of their ends.

4. The structure defined in claim 1 which further includes a spring-projected clamping device arranged to be engaged by the upper step during the movement of the step ladder by the carriage to press the same toward the abutment.

5. In a device of the class described, spinners, av carriagefor bodily moving a step ladder toward the spinners and having on its side bars knees for a top step, a support radially spaced from the spinners for an up per step to be attached to said knees for holding the same between the spinners and carriage substantially perpendicular to the axis of the spinners, and abutments on the carriage arranged to engage the heads of rivets, loosely extending through apertures in the knees and upper step, to be fed to the spinner by the carriage, said abutments also serving as guides for the knees to direct the step ladder onto the carriage and for cooperation with the support to axially align the rivets with the spinners.

6. The structure defined in claim 5 which further includes a support on the carriage for the side bars of the step ladder interme diate of their ends. V

In testimony whereof I aflix my signature.

JOHN E. KALGREN. 

